222 



FACE. 



that the orbicularis may be divided both ana- 

 tomically and physiologically into two sets of 

 fibres; an outer, or orbicularis proper, which is 

 entirely a voluntary muscle, and an inner 

 (the palpebralis) which is both voluntary and 

 involuntary in its action. These fibres may 

 act independently of each other, for in wink- 

 ing and during sleep the palpebralis contracts, 

 while the orbicularis is quiescent ; and the 

 orbicularis may contract even strongly, as when 

 we peer with the eyes under the influence of a 

 strong light, while the fibres of the pal- 

 pebrales are relaxed. It has been supposed, 

 however, by some, that during sleep the lid 

 is closed simply by the weight of the upper 

 palpebra, and the relaxation of its proper 

 elevator muscle, but this seems in contra- 

 diction to the fact that we meet with resistance 

 in endeavouring to unclose the lids of a sleep- 

 ing person. 



Corrugator supercilii, which is the associate 

 of the orbicularis palpebrarum, has been al- 

 ready described, together with the occipito- 

 frontalis, which is the antagonist of those 

 muscles. See CRANIUM, MUSCLES OF THE, 

 vol. i. p. 747. 



Levator palpebra superioris ( orbito-palpe- 

 bral), though situated within the orbit, is 

 nevertheless the direct antagonist of the palbe- 

 bralis, and is therefore properly described with 

 these muscles of the face. It is a thin trian- 

 gular .muscle, which arises by a narrow slen- 

 der tendon at the back of the orbit from the 

 inferior surface of the lesser wing of the sphe- 

 noid bone, above and in front of the optic 

 foramen ; from this origin the fibres proceed 

 almost horizontally forwards under the roof of 

 the orbit, and gradually spreading and be- 

 coming thinner as they advance, curve over 

 the globe of the eye, and are inserted into the 

 upper border and anterior surface of the upper 

 lid. 



Relations, Its upper surface is in contact, 

 behind, with the frontal branch of the ophthal- 

 mic nerve, which with some cellular tissue 

 alone separates it from the periosteum of the 

 roof of the orbit ; anteriorly with cellular tissue 

 and the palpebral fascia, which separate it from 

 the orbicularis. The lower surface behind rests 

 upon the superior rectus oculi, with which it 

 is connected by cellular tissue, and anteriorly 

 on the conjunctiva and upper lid. 



Its action is to raise the upper lid, and to 

 draw it backwards over the globe and under 

 the supra-ciliary ridge. There is no separate 

 muscle to effect the depression of the lower 

 lid, that action being occasioned, as Sir C. 

 Bell ingeniously suggested, by the protrusion 

 of the eyeball. 



Nasal region. The muscles of this region, 

 some of which are common to the upper lip, 

 are, \. the pyramidalis; 2. the levator labii 

 superior is alaque nasi; 3. the triangularis 

 nasi ; 4. the depressor al<e nasi. 



Pyramidalis is situated between the brows, 

 and may be considered as a prolongation of 

 the inner fibres of the frontalis : it is of a 

 triangular form ; its base above is continuous 

 with the fibres of the frontalis ; below it con- 



tracts and is inserted into the aponeurotic ex- 

 pansion of the triangularis nasi. It is sepa- 

 rated from its fellow slip of the opposite side 

 by a groove of cellular tissue. 



Relations. Its superficial surface adheres 

 to the skin; its deep one rests on the nasal 

 eminence of the frontal bone, the nasal bones, 

 and part of the lateral cartilage of the nose. 



Use. If this muscle acts at all on the nose, 

 it is by drawing up the skin when the occipito- 

 frontalis is in action. Its more probable use 

 is to give a fixed point to the frontalis, and to 

 draw down the inner extremity of the brows 

 and the skin between them. 



Levator labii superioris al&que nasi. (T, 

 Jig. 134.) This is a thin, long, triangular 



Fig. 134. 



muscle, placed nearly vertically on each sid e 

 of the nose. It arises narrow from the outer 

 surface of the nasal process of the upper max- 

 illary bone, immediately beneath the tendon 

 of the orbicularis palpebrarum. It descends 

 obliquely outwards, becoming broader, arid 

 terminates inferiorly by two slips, an internal 

 short one, which is attached to the cartilage 

 of the ala nasi, or to the fibrous membrane 

 which invests it; and an outer longer slip, 

 which is attached to the skin of the upper lip 

 near the nose, and mingles its fibres with the 

 transversalis nasi, the levator labii superioris 

 proprius, and the orbicularis oris. 



Relations. Covered by the skin, and over- 

 lapped a little above by the orbicularis pal- 

 pebrarum, this muscle covers the nasal process 

 of the upper maxillary bone, the triangularis 

 nasi, and the depressor alee nasi. Its inner 

 border above corresponds to the pyramidalis. 



Its action is to raise the ala of the nose and 

 the adjacent part of the upper lip; in so doing 

 it dilates also the nostril and becomes a muscle 

 of inspiration. When strongly thrown into 

 action, it corrugates the skin of the nose trans- 

 versely. 



